Method for operating an electric drivetrain for a working machine, electric drivetrain for a working machine, and working machine

Abstract

A method for operating an electric drivetrain of a working machine is provided wherein the drivetrain comprises a work drive with an electric work motor and a travel drive with an electric travel motor and vehicle wheels, wherein the working machine experiences a speed deceleration from the outside that may result in a braking force acting on the vehicle wheels lower than a driving force acting on the vehicle wheels due to a moment of inertia of the travel motor. The method includes supplying the travel motor with a power in a direction opposite to an operating direction of the travel motor in order to reduce a rotational speed of the travel motor, if it is detected in advance using a situation detection that the braking force acting on the vehicle wheels as a result of the speed deceleration is lower than the driving force acting on the vehicle wheels.

The invention claimed is: 
     
         1 . A method for operating an electric drivetrain of a working machine,
 wherein the electric drivetrain comprises a work drive with an electric work motor and a travel drive with an electric travel motor and vehicle wheels, the electric work motor and the electric travel motor being electrically connected to a battery,   wherein the working machine experiences a speed deceleration from the outside, and   wherein a braking force acting on the vehicle wheels due to the speed deceleration can be lower than a driving force acting on the vehicle wheels due to a moment of inertia of the electric travel motor, the method comprising:   supplying the electric travel motor with electrical power from the battery, the supplied electrical power being in a direction opposite to an operating direction of the electric travel motor in order to reduce a rotational speed of the electric travel motor, based on a detection in advance using a situation detection that the braking force acting on the vehicle wheels as a result of the speed deceleration is lower than the driving force acting on the vehicle wheels.   
     
     
         2 . The method according to  claim 1 , wherein the situation detection is carried out using an environment sensor system. 
     
     
         3 . The method according to  claim 1 , wherein the situation detection is carried out by means of an acceleration sensor system and/or a tilt sensor system. 
     
     
         4 . The method according to  claim 1 , wherein the situation detection is carried out using a slipping clutch, wherein a clutch pressure is specified in such a way that a maximum torque transmissible by the clutch is lower than a braking torque resulting from the braking force. 
     
     
         5 . The method according to  claim 1 , wherein the situation detection is carried out using speed monitoring and/or torque monitoring of the travel drive. 
     
     
         6 . The method according  claim 1 , wherein the situation detection is carried out using absolute speed monitoring. 
     
     
         7 . The method according to  claim 1 , wherein the situation detection is carried out by monitoring a power demand of the travel drive. 
     
     
         8 . The method according to  claim 1 , wherein the situation detection is carried out by of monitoring a behavior of the work drive. 
     
     
         9 . The method according to  claim 1 , wherein the situation detection is carried out by monitoring a driving behavior of an operator of the working machine, and further comprising learning in advance a typical driving behavior of the operator in preparing for an event of an imminent speed deceleration. 
     
     
         10 . The method according to  claim 1 , further comprising assisting a speed reduction of the electric travel motor by a gear downshift. 
     
     
         11 . The method according to  claim 1 , wherein supplying the electric travel motor with the electrical power comprises supplying the electric travel motor with an electrical current that powers the electric travel motor in a direction opposite a rotation direction of the electric travel motor during the speed deceleration of the work machine. 
     
     
         12 . The method according to  claim 1 , wherein the electric drivetrain comprises an inverter and wherein the inverter is configured to directly control the electric travel motor by providing the electrical power supplied by the battery to the electric travel motor. 
     
     
         13 . An electric drivetrain for a working machine, comprising: a work drive with an electric work motor;
 a travel drive with an electric travel motor and vehicle wheels; and   a battery electrically connected to the electric work motor and the electric travel motor,   wherein the vehicle wheels are rigidly drivably coupled or rigidly drivably couplable to the electric travel motor, so that in the event of a speed deceleration acting on the working machine from the outside that results in a braking force acting on the vehicle wheels the electric drivetrain is configured to detect in advance by a situation detection whether the braking force acting on the vehicle wheels due to the speed deceleration is lower than a driving force acting on the vehicle wheels due to a moment of inertia of the electric travel motor, and   wherein the travel drive is configured to supply electrical power from the battery, the electrical power being supplied to the electric travel motor in a direction opposite to an operating direction of the electric travel motor to reduce the rotational speed when the situation detection detects that the braking force is lower than the driving force.   
     
     
         14 . A working machine comprising the electric drivetrain according to  claim 11 . 
     
     
         15 . A working machine according to  claim 14 , wherein the working machine is configured as a wheel loader. 
     
     
         16 . A method for operating an electric drivetrain for a working machine, the electric drivetrain having a work drive with an electric work motor and a travel drive with an electric travel motor and vehicle wheels, wherein the vehicle wheels are rigidly drivably coupled or rigidly drivably couplable to the electric travel motor, the method comprising:
 detecting in advance of a speed deceleration acting on the working machine from the outside, by a situation detection, whether a braking force acting on the vehicle wheels due to the speed deceleration is lower than a driving force acting on the vehicle wheels due to a moment of inertia of the electric travel motor, and   based on the situation detection detecting that the braking force is lower than the driving force, supplying from a battery of the travel drive, electrical power to the electric travel motor in a direction opposite to an operating direction of the electric travel motor to reduce a rotational speed of the electric travel motor.